I am planning for a trip to these four cities. I have my conference at Budapest. So, I am planning to start my tripfrom Vienna, den attending the Confenrence in Budapest , from there moving to warsaw, Prague and return to Viena. This will be fo 7 days. Suggest me better options or any other change and suggesstion in the Itinary.
With only seven days at your disposal, you'd spend much of your time traveling from city to city without enjoying them. For example, it takes 10 to 11 hours by rail from Budapest to Warsaw; and 7 to 8 hours by rail from Warsaw to Prague. It's about 7 hours by rail from Budapest to Prague; and 4 hours from Prague to Vienna. You could take a night train or a night bus to save time; but you are likely to be exhausted from all that travel.
Suggest you concentrate on Vienna and Budapest. Budapest is only 2.5 to 3 hours by train from Vienna. For rail schedules, see this link: https://www.bahn.com/i/view/USA/en/index.shtml, or https://www.oebb.at/en/
Austrian Railways (OBB) offers discounted Sparschiene tickets, allowing you to travel inexpensively to Budapest, Prague and other cities for as little as 19 euros (even cheaper to other cities in Austria). You can book these tickets online in advance with a credit card. See this link: http://www.oebb.at/en/angebote-ermaessigungen/sparschiene. The savings are substantial. I recently bought a Sparschiene ticket from Vienna to Zeltweg, Austria, for 9 euros. The regular fare is 39 euros.
Since you're going to be in Vienna, I recommend taking OBB's rail/boat day trip from Vienna to Melk to visit the spectacular abbey library there. The boat ride on the Danube passes towns, villages and vineyards, either going to/from Melk.
P.S. There are some people who simply like to ride buses and trains, going from place to place, connecting the dots, so to speak. I did that when I first started traveling, making full use of my student rail pass in Europe. I hopped from city to city, sleeping at nights on trains to save time and money. But, after a while, you tire of that; and you realize that it was a mistake.
[ Edit: Edited on 24-May-2016, at 04:44 by berner256 ]